Glass sheet bending apparatus



1963 A. DAMMERS 3, 06,464

' GLASS SHEET BENDING APPARATUS Filed Feb. 17. 1959 4 sheets-sheet 1 INVENTOR.

AUGUST DAMMERS WMM ATTOR E YS Oct. 8, 1963 A. DAMMERS 3,106,464

GLASS SHEET BENDING APPARATUS Filed Feb. 17, 1959 4 Sheets-Sheet 2 INVENTOR.

AUGUST DAM MERS W @m Mg ATTOR N Oct. 8, 1963 A DAMMERS GLASS SHEET BENDING APPARATUS 4 Sheets-Sheet 3 Filed Feb. 17, 1959 INVENTORQ AUGUST DAMMERS BY ATTOR Ys A. DAMMERS GLASS SHEET BENDING APPARATUS Oct. 8, 1963 4 Sheets-Sheet 4 Filed Feb. 17, 1959 m m m m AUGUST DAMMERS (flaw, MQ QW W ATTOR Y5 3,106,464 GLASS SHEET BENDING APPARATUS August Dammers, Herzogenrath-Merkstein, Germany, assiguor .to Compagnie de Saint-Gobain, Paris, France Filed Feb. 17, 1959, Ser. No. 793,900

Claims priority, application France Feb. 18, 1953- 16 Claims. (Cl. 65-291) This invention relates to an apparatus for bending or curving plastic sheets, the apparatus being particularly adapted for the bending of sheets of glass presented thereto at the temperature necessary to their bending. The apparatus includes as essential elements thereof a rigid convex form or die and a flexible element, the sheet to be bent being interposed between the die and the element and being progressively bent as the die and element approach each other.

i The apparatus of the invention is particularly useful in the bending of safety glazings, such as Windshields for automobiles, which sometimes require bent glass sheets of shapes which existing bending apparatus cannot conveniently produce. This is especially true when the bent glass sheet includes parts which are curved cylindrioally and parts curved conically, and even parts having spherical curvatures. In accordance with a first embodiment of the invention, in order to secure bending of plastic sheets to such complex shapes, there is employed a flexible element made up of a frame formed of thin bands articulated at'their extremities. Such bands, which are themselves flexible, may, by reason of such articulations, be displaced through small distances with respect to each other, thereby permitting the frame to yield as required to conform to the shape of the rigid convex die with which it cooperates. Such yieldability of the element allows it to adjust its shape as required by the die which may, for example, have different zones thereof having surfaces which are plane, cylindrical, conical, and various combinations thereof.

In order to equalize the pressure exerted on the sheet of plastic material which is to be bent by the interaction of the die and of the element, the bands making up the element, particularly those of greatest length, are reinforced by one or more additional bands. Such additional bands, which may be in the nature of leaf springs, are permitted to slide in the directions of their lengths in stirrups which are preferably of such construction as to allow the bands to be held in fixed positions, as desired. The frame may be applied directly to the sheet to be bent but, particularly when the sheet is made of glass and is heated to an elevated temperature, the sheet-contacting members of the frame are preferably provided with a refractory covering which is deformable with the frame to the eventual shape to which the sheet'is to be bent.

Instead of being made up of articulated bands, the frame may, in accordance with another illustrative embodiment, consist of a continuous flexible elastic member which is bent to form a closed frame, such continuous member being mounted on an articulated assembly having a shape corresponding to that of the sheet to be bent.

In preferred embodiments of theinvention the flexible frame is fixedly mounted at its middle on :a support and disposed opposite the die. Means are providedto move the die and frame relatively toward and away from each other so as to grip a sheet to be bent between them and progressively to bend the sheet asthe die and frame come together. 1

In accordance with the invention the'extrernities of the frame are selectively formed and bent' by controllable means whereby to permit the frame to mate with the die.

- In the embodiments shown,.such frame-deforming means are fluid actuated pistons. In another embodiment of the United States Pate ment, the turning of such arms being controlled by fluid.

pistons. In such last embodiment, in order to maintain the frame stretched at the beginning of the bending procedure, they are provided springs which are interposed element of FIG. 1, the view being between the ends of the pivoting arms and the ends of the frame.

Int-he following specification there are described three preferred embodiments of the bending apparatus of the invention. All such embodiments are particularly adapt ed for, but not restricted to, the bending of vertically suspended sheets of glass. It is to be expressly understood that the apparatus may be employed to an advantage in the bending of sheets of other materials, and that the drawings are for the purpose of illustration only and are not intended as a definition of the limitations of the invention.

In the drawings, wherein like reference characters refer to like parts throughoutthe several views,

FIG. 1 is a view in plan of a first embodiment of sheet bending apparatus in accordance with the invention;

' FIG. 2 is a. view in elevation of the flexible bending taken along the line 2-2 of FIG. I;

FIG. 3 is a fragmentary view in section of a portion of the sheet engaging frame member of the flexible ele ment;

FIG. 4 is a fragmentary view in elevation of a sheetengaging frame of the flexible element;

FIG. 5 is a view in vertical section through such flexible sheet engaging frame element, the section being taken along the line 5-5 of FIG. 1;

FIG. 6 is :a view in plan of a second embodiment of sheet bending apparatus made in accordance with the invention;

. FIG. 7 is a view in elevation of the flexible element of the apparatus of FIG. 6, the element being shown in ex tended condition;

FIG. 7a shows a detail in section of the flexible element;

FIG. 8 is a view elevation of a third embodiment of sheet bending apparatus in accordance with the invention;

FIG. 9 is a view in plan of the apparatus of FIG. 8; and

FIG. 10 is a fragmentary view in plan on an enlarged scale of the portion of the apparatus of FIG. 9 at the end of one of the pivoted arms and of the end of the flexible frame member connected thereto.

In FIGS. 1 and 2 the flexible element 1, between which and a rigid convex die or bending form 2 a sheet of glass F is disposed to be bent, is made up of thin bands 4, 5, 6 and 7, made, for example, of sheet iron or steel. Form 2 a has a forward curved, glass-engaged surface and a rear, reinforcing web portion 50, as shown. Such bands are connected in a non-rigid manner at their extremities 3, 3', 3", and-3" as by rivets the heads of which only loosely engage the bands. Such construction thus permits a limited degree of motion between the various parts of the flexible element. The frame 1 is eventually provided with cross bands 8, 9, 10, and 11, extending between the opposed longer bordering bands 4 and 5 of the frame,

such cross bands likewise being connected at their ends in a non-rigid manner to the bands 4=and 5.

As shown in FIG; 1, the two longest bands 4 and 5 carry at the rear thereof at least one, and preferably a plurality of, additional bands 12 whichfunction as leaf springs. Such additional bands 12 slide to a limited extent in stirrup-like members 13 which are shown more Patented Oct. 8, 1963 I 3 threaded member 13a having an inwardly disposed head 13b, whereby the additional band 12 may be locked in a desired position or may be allowed to slide longitudinally with a desired degree of frictional restraint.

At the extremities of the bands 4 and 5 there are provided reinforcing elements 14 and 14, which extend through stirrup-like members in the same manner as do bands 12. Such reinforcing bands 14 and 14' facilitate the bending of the ends of the sheet P which, in the embodiments shown, are to lie substantially in planes, designated 15 and 15, on the ends of die 2. The extremities of the frame are reinforced by auxiliary bands 16, 16, 17, and 17. Such latter auxiliary bands serve to support at such ends of the frame a continuous ribbon 18 of refractory material which contacts the sheet of glass during the course of the bending operation. FIGS. 4 and 5 show the ribbon 18 as being made up of a flexible band 19 and by a refractory facing 20. The band 19 is held between opposed jaws 21 and 21 of a sheet iron clip, such clip being riveted to the frame at 22 and 22.

The frame is secured at each of its ends 23 and 24 by connecting means 25 and 26 t0 the ends of the piston rods of the respective prime movers shown as fluid operated motors 27 and 28. Such fluid operated motors have the ends of the casings or cylinders thereof pivotally mounted on a transverse frame member 29 which is rigidly secured to central supports 30 and 30a.

The sheet of glass P which is to be bent is heated near to softening and is supported, by means not shown, in vertical position between the frame 1 and the die 2 with the two such members retracted from each other as shown in FIG. 1. Following this, the elements 1 and 2 are caused to approach each other. In the embodiments shown member 30 carrying the flexible bending frame is fixedly mounted, whereas die 2 is mounted for reciprocation toward and away from the flexible frame. Thus the element 51 is a piston rod having a piston 70 connected thereto. The piston and piston rod are parts of a horizontally disposed double acting fluid motor having a cylinder designated 71. With the parts in the position shown in FIG. 1, piston 70 and rod 51 are advanced to the left carrying with it the glass sheet F and causing the sheet to contact the flexible ribbon 18. Such contact of the sheet of glass by the ribbon 18 first occurs in its central or median zone at support 30a, and also presses such central zone of the sheet against the die 2. As the frame 1 and die 2 continue to approach each other, the sheet of glass F is progressively bent and applied to the die, the frame 1 yielding to allow it also to assume a form complementary to the die. After the frame 1 and the die 2 have approached each other sufliciently to cause the ends of a sheet F to begin to be bent, that is, so that the ends of the sheet lie tangent to the curved surfaces of die 2 immediately adjacent the planes 15 and 15, fluid under pressure is admitted to cylinders 27 and 28 to thrust the piston rods therefrom, thereby bending the ends of frame 1 over the ends of the die 2 to cause the ends of sheet F to be strongly pressed against and to conform to the planes of zones 15 and 15 on the ends of the die.

In FIGS. 6, 7, and 7:: there is shown a second embodiment of sheet bending apparatus in accordance with the invention. In such embodiment the flexible frame is made up of a continuous flexible member 31 closed on itself which is bent to form an open frame generally of the shape of the sheet blank which is to be bent. Frame member 31 is secured in its central position 31a to an axial support 32. As is shown in FIG. 7a, the member 31 is composed of a central helical spring 34 which is provided with a heat resistant sheath 33 which may be made, for example, of flexible refractory plastic material or of any other suitable material. Arms 35 and 36 are fastened on support 32. At the ends of the arms 35 and 36 there are pivotally connected links 37 and 38, the opposite ends of which are connected to vertical frame members 39 and 40. Pivotally supported on a transverse frame member aflixed to central support 32 are the cylinders of two prime movers shown as fluid operated motors 43 and 44. The piston rods 41 and 42, respectively, of such motors are pivotally connected to links 37 and 38 secured, respectively, to vertical frame members 39 and 40. The frame member 31 is held between the frame members 39 and 40 by means such as brackets 39a, 39b, 40a, and 40b. Frame member 31 is provided with retractors or braces 46, 47, 48 and 49 which are adjustable to vary the shape of the frame in accordance with contour of the sheet which is to be bent.

As shown in FIG. 6, the frame member 31 may be deformed so as to be applied effectively to the surface of the convex die 50. When the frame is in its resting position, the piston rods 41 and 42 are fully retracted within their respective cylinders 43 and 44, so that the elastic frame 31, under the action of arms 37 and 38, lies substantially in the vertical plane of its median or central position 31a. After the frame 31 has been first applied to the rigid convex die 50, with a sheet F to be bent between the frame 31 and the die 50, the frame and die first contact the central portion of sheet F. Thereafter the frame begins to bend the sheet around die in directions extending oppositely from the central vertical transverse plane thereof. At an appropriate time in the bending operation, fluid under pressure is admitted to the rear of each of motors 43 and 44 so as to thrust the piston rods thereof outwardly. The sheet of glass is thus smoothly pressed around the curved ends of die 50 by reason of the deformation of the bending frame 31 by the motors. It will be seen that in this operation the sheet of glass is first applied to the die 50 at its central zone, and thereafter is progressively and smoothly pressed around the die, including the opposite ends of such die.

The third disclosed embodiment of the sheet bending apparatus of the invention is shown in FIGS. 8, 9, and 10. Such apparatus is particularly useful for bending sheets thereby into the so-called panoramic form. Such apparatus includes a support 51 which carries a rigid convex die 52, and a support 53 which is in alignment with and opposite the support 51. Support 53 carries a flexible "bending frame 55. Such frame is rigidly mounted at its center on the support 53 and at its ends is yieldably connected to the outer ends of two curved arms 54 and 54' which are pivotally mounted on vertical pivot pins secured to central support 53. The arms 54 or 54' are under the control of fluid operated motors 57 and 57', the rear ends of the casings or cylinders of which are pivotally supported on a transverse frame member 58 which is secured to support member 53. The outer ends of piston rods 56 of motors 57 and 57' are pivotally connected to the respective arms 54 and 54', intermediate the lengths thereof.

Assuming that a sheet of glass 59 heated near softening has been suspended in vertical position between the flexible frame 55 and the rigid convex die 52, the bending operation proceeds as follows:

The flexible frame 55 and the die 52 are caused to approach each other and to grip sheet 59 between the rigid central position of frame 55 at support 53 and the central portion of die 52. Continued approach of the frame and die toward each other causes the frame to be bent to conform to the gently curving portions of die 53 lying on opposite sides of the central zone thereof. When the frame and die have approached each other sufiiciently for the still plane end portions of sheet 59 to lie tangent to the entering, forward ends of the zones of accentuated curvatures connecting the forward and side surfaces of die 52, the fluid actuated motors 57 and 57 are actuated to thrust the piston rods outwardly therefrom. This causes the outer ends of arms 54 and 54 to approach the confronting ends of die 53, thereby to cause the flexible frame 55 to be bent down alongside the end surfaces of arms 54 and 54, there is employed the means connecting the ends of the frame and the ends of each of the arms which is more particularly shown in FIG. 10. The elements associated witheach of arms 54, 54 are similar; those parts associated with arm 54 are designated by the same reference characters as those associated with arm 54 but with an added prime.

At the end of arm 54- there is provided an angularly disposed passage in a boss 60 Within which an elongated pin 61 is slida-bly mounted. Such pin carries at its lower end an articulated element 63, which is connected to the end of frame 55 by a bracket 64. A coil compression spring 65 is disposed between element 65- and the boss 60 on arm 54. Such coil spring maintains the frame 55 under tension at the beginning of the bending operation, and yields to compensate for the difference in length between the arc and the chord of the path of the end of the arm during bending. At the end of the bending op eration, the frame 55 is strongly compressed by means of pins 66, 66' which extend through a flange on the respective one of the arms 54 and 54'. The inner ends of pins 66 engage the rear surface of frame 55 and thrust it strongly against glasssheet 59; such sheet in turn is thrust in the opposite direction by die 52. Pins 66 are preferably adjustable along their axes on the respective arms 54 and 54, as by having screw threaded engagement with the flange on the arm through which they pass.

As many apparently widely different embodiments of the present invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments shown in the drawings and above described.

What is claimed is:

1. Apparatus for bending heated thermoplastic sheets such as glass and the like, said apparatus comprising a convex, rigid bending form and a flexible bending form each having a heat resistant sheet engaging face, said forms being mounted in opposing cooperating position to engage the opposite broad surfaces of a thermoplastic sheet and to bend said sheet between them, a central support for the flexible form, means to advance the forms toward each other, said flexible bending for-m having a flexible bending frame fixedly mounted in its central portion on said support, and means selectively to produce deformation of the ends of the flexible bending frame to permit them to conform to the curvature of the zones of the rigid bending form cooperating therewith as the bending operation progresses.

2. Apparatus as defined in claim 1, wherein the flexible bending frame is initially substantially flat at the beginning of a sheet bending operation, and the means to produce deformation of the ends of the flexible bending frame selectively holds the flexible bending frame in extended substantially flat condition and produces deformation of the ends of the flexible form to the curvature of the zones of the rigid bendingform cooperating therewith as the bending operation progresses.

3. Apparatus as defined in claim 2, comprising oppositely disposed arms pivotally mounted on said central support, the ends of the flexible bending frame being secured to the outer ends of said arms, and means for thrusting the arms to cause the outer ends thereof to move closer together andpartially to wrap the ends of the flexible bending frame around the opposite ends of the rigid bending form toward the end of the sheet-bending operation.

4. Apparatus as defined in claim 3, comprising resilient means attaching the ends of the frame to the ends of the arms, said resilient means allowing the ends of the frame to yield relative to the arms as the bending operation progresses.

5. Apparatus as defined in claim 4, wherein the outer ends of the arms are curved so as to present inner surfaces which are generally complementary to the portions of the rigid convex bending form which they confront.

6. Apparatus as defined in claim 5, comprising a plurality of adjustable abutment means mounted on the forward faces of the arms, said abutment means engaging the rear edge of the flexible frame when the frame lies partially wrapped about the rigid'convex bending form.

7. Apparatus as defined in claim 1, wherein the means to produce deformation of the ends of the flexible bending frame is mounted on said frame.

8. Apparatus as defined in claim 7, wherein said means to produce deformation of the ends of the flexible bending form comprises individual prime movers, one

mounted at each end of the flexible bending frame to defor-m the respective ends thereof.

9. Apparatus as defined in claim 8, wherein the prime movers are fluid actuated expansible motors, one end of each motor being secured to the respective end of the flexible bending frame and the other end being secured to a frame member rigidly secured to said central support.

10. Apparatus as defined in claim 1, wherein the flexible bending frame is made up of thin flexible loosely articulated bands.

11. Apparatus as defined in claim 10, comprising reinforcing leaf springs aligned with and lying alongside the backs of the flexible bands of the flexible bending frame and slidably connected thereto.

12. Apparatus as defined in claim 11, comprising stirrup-like clips attached to the flexible bands, said reinforcing leaf springs being slidable in said clips.

13. Apparatus as defined in claim 12, wherein said clips include adjustable means engaging the leaf springs whereby to impose a selected frictional restraint against the sliding of the leaf springs through the clips.

14. Apparatus asdefined in claim 1, wherein the flexible sheet-engaging frame is a continuous flexible sheetengaging member closed onitself and generally conforming to the outline of the sheet to be bent.

15. Apparatus as defined in claim 14, comprising a flexible refractory sheet-engaging facing on the flexible bending frame.

16. Apparatus as defined in claim 14, wherein the continuous flexible sheet-engaging member comprises an elongated coil spring extending centrally therewithin and a heat resistant sheath disposed about said spring.

References Cited in the file of this patent UNITED STATES PATENTS France Nov. 23, 1955 

1. APPARATUS FOR BENDING HEATED THERMOPLASTIC SHEETS SUCH AS GLASS AND LIKE, SAID APARTUS COMPRISING A CONVEX, RIGID BENDING FORM AND A FLEXIBLE BENDING FORM EACH HAVING A HEAT RESISTENT SHEET ENGAGING FACE, SAID FORMS HAVING MOUNTED IN OPPOSING COOPERATING POSITION TO ENGAGE THE OPPOSITE BROAD SURFACES OF A THERMOPLASTIC SHEET AND TO BEND SAID BETWEEN THEM, A CENTRAL SUPPORT FOR THE FLEXIBLE FORM, MEANS TO ADVANCE THE FORMS TOWARD EACH OTHER, SAID FLEXIBLE BENDING FORM HAVING A FLEXIBLE BENDING FRAME FIXEDLY MOUNTED IN ITS CENTRAL PORTION OF SAID SUPPORT, AND MEANS SELECTIVELY TO PRODUCE DEFORMATION OF THE ENDS OF THE FLEXIBLE BENDING FRAME TO PERMIT THEM TO CONFORM TO THE CURVATURE OF THE ZONES OF THE RIGID BENDING FORM COOPERATING THEREWITH AS THE BENDING OPERATION PROGRESSES. 